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Wow! It looks like I could not have chosen a better week for Zombie Week here at Teddy's Rat Lab. I had initially planned on just having a couple of posts, but it looks like I can fill the week (and more) just with Science, News and Comment. However, I do promise to have a little fun with the idea of Zombie Wars and the Zombie Apocalypse later (and possibly into next week).
But for now, Sunday and Monday, I planned out this week with the contest announcement and topic tie-in to Schlock Mercenary. Wednesday was to be a scholarly look at the nonmagical concept of Zombies and think of ways to get the "Zombie effect" purely from scientific methods. I had planned that Friday I would take a look at Zombies in literature and media and discuss some of the origins of the ideas, then have a bit of fun over the weekend. [And by the way, if you are getting this by Facebook or email, please visit the website using the link above and participate in the "Messy ways to kill Zombies poll. It will run through next Monday and will be used in the later discussion.]
However, that plan has already changed. Today I was websurfing and found this gem: http://www.dailymail.co.uk/news/article-2143584/Scopolamine-Powerful-drug-growing-forests-Colombia-ELIMINATES-free-will.html
SO - I am postponing Friday's post on Zombie Lit and today we will discuss... The Zombie Drug!
Let's start with the drug itself. The Daily Mail article mentions the "Devil's Breath" powder made from flowers of the Borrachero tree. These trees are what are known as nightshades, plants that produce the alkaloid drugs of the solanum family. [Not to be confused with the fictional "Solanum virus" of The Zombie Survival Guide.] This has got to be the strangest taxonomic classification in the field of biology, because it encompasses so many disparate types of plant: flowering trees, vines, roots and legumes. On the other hand, all of these plants produce similar substances of pharmaceutical significance - i.e. the nightshade alkaloids. Devil's Breath is essentially a powdered plant extract consisting primarily of the anti-acetylcholine drug: scopolamine.
The pharmacological actions of scopolamine are very well known. The figure at the right shows scopolamine and the similar drug atropine. These two drugs are quite frequently used to treat conditions in which there is too much acetylcholine present at neuron synapses. There are a few cases in which that may be necessary - organophosphate (insecticide or nerve gas) poisoning, motion sickness, asthma/bronchospasm. In the first case, the poison affects the acetylcholinesterase enzyme which breaks down acetylcholine and normally acts to regulate activation of acetylcholine-dependent synapses. In the latter two cases, overstimulation of acetylcholine neurons results in nausea, excess salivation, excess lacrymation (tears), diarrhea, and build-up of fluid in the lungs; scopolamine is an antagonist which blocks the excess neural activity by blocking the acetylcholine receptor. Scopolamine is also used in some cases for the treatment of depression and bipolar disorder.
The effects of scopolamine in the central nervous system are primarily to produce amnesia - by blocking the acetylcholine receptors, patterns of neural activity cannot be consolidated into long-term memory. Scopolamine is used in the laboratory to mimic the effects of amnesia and disease states such as Alzheimer's Disease. Scopolamine is also used illicitly to produce hallucinations and anesthesia - however this use is dangerous due to the low levels required for toxicity (10 micrograms per kilogram of total body weight if given IV, 100 micrograms/kg intramuscular, but over 1 milligram/kg oral/inhaled). Accepted medicinal uses tend to be about 1/10 to 1/4 the toxic dose, but the moderate doses can also trigger adverse reactions such as malignant hyperthermia.
Is there truth to the "Zombie" claims?
Well, in a way, they are true. Scopolamine has been used in the past for prisoner interrogation (along with sodium pentothal, another amnesia-producing anesthetic). It easily passes the blood-brain barrier, and can easily cause hallucinations and amnesia. The "lack of mental function" claimed for the drug results from a condition known as hypofrontality in which the suppression of neuron activity (particularly acetylcholine neurons) leads to a lack of the type of cognitive activity that neuroscientists call executive function. So, in essence, overdoses of scopolamine can indeed cause a condition in which the subject shows no awareness and no resistance to suggestion. However, it should be noted that this is the "brainless" variety of Zombie - no voluntary motion,no conscious thought - and is a far cry from the urban legend reports of people being forced to perform many acts against their will after just a brief exposure to scopolamine.
Should travelers to South America be frightened of being turned into Zombies by a brief whiff of plant extract (and dropping dead of scopolamine toxicity a few hours later)?
In short, no.
To start with, the flower of the Borrachero tree, once dried and ground, is going to contain just a few grams of material, but only a small portion is active drug - maybe 1-5 milligrams. Given that about 10-20 milligrams of scopolamine-derived chemicals are used as a bronchodilator for chronic obstructive pulmonary disease, getting a whiff of "Devil's Breath" may give you a slight dry mouth - but at least you'll breathe easier! The actual psychoactive effects (anesthesia, amnesia, hallucination) will require about 40-50 times the dosage from simply breathing the powder (not to mention the fact that only a small amount of "blown powder" will actually be ingested. This is not to say that individuals who smoke solanum extracts are not endangering themselves, as they actually do ingesting amounts close to the toxic dose levels.
There you have it. A real-life Zombie drug, but not too much risk of a Zombie outbreak from this urban legend. Stay tuned this week for more Zombie Science... at Teddy's Zombie Lab!